Rotary drilling operations have long been preferred for drilling deep wells such as for oil and gas applications. The most predominant approach for rotary drilling is to provide a power driven rotary table in a drilling platform through which a Kelly bar slidingly engages to permit vertical movement. The Kelly bar is attached to the drill string. Revolutions of the rotary table drive the Kelly bar which slips through the rotary table with the advancement of the bit at the end of the drill string. This system has the advantage that the machinery for ultimately turning the drilling string can be placed on the platform itself. However, this equipment is heavy and cumbersome and is not portable in the conventional sense. Further, this system requires extensive set up and take down.
An alternative driving unit for rotary drilling has been to dangle a rotary drive from a hook at the end of a block line of a drilling rig. However, these attempts for rotary power driven swivels have produced power drive systems which are heavy and cumbersome and preclude reorienting the vertical axis of the output shaft or saver-sub for connection to drill pipe in an orientation other than vertical alignment. Thus, each piece of the drill pipe must be vertically aligned for the convenience of the power drive unit. This requires relatively extensive handling to either stand the pipe on its end within the drilling rig by snaking the pipe up among the cross bars or, alternatively, to vertically stand the drilling pipe by dropping it into a "mouse hole" adjacent the drilling rig, again requiring that the pipe be lifted and then set down in separate operations from that of attaching or making up the power drive system to the drill pipe.
It is an object of the present invention to provide a portable drive system capable of rapid set up in support of the drilling rig for both drilling a well and for reworking a well.
Another object of the present invention to provide a rotary power drive for drilling or reworking oil wells which is suspendable upon a block line of a drilling rig, yet is capable of making up with a substantially horizontal drill pipe, thereby eliminating time consuming and awkward orientation of the drilling pipe to a vertical position prior to make up.
It is a further object of the present invention to increase the ease of handling and safety for power drive systems suspended from the block line of a drilling rig.
Finally, it is an object of the present invention to automate drilling operations.